The first and foremost intent of our present study is to design a perovskite solar cell favorable for realistic applications with excellent efficiency by utilizing SCAPS-1D. To ensure this motive, the detection of a compatible electron transport layer (ETL) and hole transport layer (HTL) for the suggested mixed perovskite layer entitled FA0.85Cs0.15Pb (I0.85Br0.15)3 (MPL) was carried out, employing diver ETLs such as SnO2, PCBM, TiO2, ZnO, CdS, WO3 and WS2, and HTLs such as Spiro-OMeTAD, P3HT, CuO, Cu2O, CuI, and MoO3. The attained simulated results, especially for FTO/SnO2/FA0.85Cs0.15Pb (I0.85Br0.15)3/Spiro-OMeTAD/Au, have been authenticated by the theoretical and experimental data, which endorse our simulation process. From the detailed numerical analysis, WS2 and MoO3 were chosen as ETL and HTL, respectively, for designing the proposed novel structure of FA0.85Cs0.15Pb (I0.85Br0.15)3-based perovskite solar cells. With the inspection of several parameters such as variation of the thickness of FA0.85Cs0.15Pb (I0.85Br0.15)3, WS2, and MoO3 including different defect densities, the novel proposed structure has been optimized, and a noteworthy efficiency of 23.39% was achieved with the photovoltaic parameters of VOC = 1.07 V, JSC = 21.83 mA cm-2, and FF = 73.41%. The dark J-V analysis unraveled the reasons for the excellent photovoltaic parameters of our optimized structure. Furthermore, the scrutinizing of QE, C-V, Mott-Schottky plot, and the impact of the hysteresis of the optimized structure was executed for further investigation. Our overall investigation disclosed the fact that the proposed novel structure (FTO/WS2/FA0.85Cs0.15Pb (I0.85Br0.15)3/MoO3/Au) can be attested as a supreme structure for perovskite solar cells with greater efficiency as well as admissible for practical purposes.